==================================================================
BUG: KCSAN: data-race in ptrace_check_attach / ptrace_stop

read to 0xffff88809a1c54c8 of 8 bytes by task 22719 on cpu 0:
 ptrace_freeze_traced kernel/ptrace.c:178 [inline]
 ptrace_check_attach+0x102/0x270 kernel/ptrace.c:247
 __do_sys_ptrace kernel/ptrace.c:1267 [inline]
 __se_sys_ptrace kernel/ptrace.c:1237 [inline]
 __x64_sys_ptrace+0x104/0x220 kernel/ptrace.c:1237
 do_syscall_64+0xcc/0x370 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

write to 0xffff88809a1c54c8 of 8 bytes by task 22649 on cpu 1:
 ptrace_stop+0x2f2/0x520 kernel/signal.c:2242
 ptrace_signal kernel/signal.c:2485 [inline]
 get_signal+0xc69/0x1320 kernel/signal.c:2630
 do_signal+0x3b/0xc00 arch/x86/kernel/signal.c:815
 exit_to_usermode_loop+0x250/0x2c0 arch/x86/entry/common.c:159
 prepare_exit_to_usermode arch/x86/entry/common.c:194 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:274 [inline]
 do_syscall_64+0x353/0x370 arch/x86/entry/common.c:300
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 22649 Comm: syz-executor.3 Not tainted 5.4.0-rc3+ #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================
Kernel panic - not syncing: panic_on_warn set ...
CPU: 1 PID: 22649 Comm: syz-executor.3 Not tainted 5.4.0-rc3+ #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0xf5/0x159 lib/dump_stack.c:113
 panic+0x210/0x640 kernel/panic.c:221
 kcsan_report.cold+0xc/0x10 kernel/kcsan/report.c:302
 __kcsan_setup_watchpoint+0x32e/0x4a0 kernel/kcsan/core.c:411
 __tsan_write8 kernel/kcsan/kcsan.c:36 [inline]
 __tsan_write8+0x32/0x40 kernel/kcsan/kcsan.c:36
 ptrace_stop+0x2f2/0x520 kernel/signal.c:2242
 ptrace_signal kernel/signal.c:2485 [inline]
 get_signal+0xc69/0x1320 kernel/signal.c:2630
 do_signal+0x3b/0xc00 arch/x86/kernel/signal.c:815
 exit_to_usermode_loop+0x250/0x2c0 arch/x86/entry/common.c:159
 prepare_exit_to_usermode arch/x86/entry/common.c:194 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:274 [inline]
 do_syscall_64+0x353/0x370 arch/x86/entry/common.c:300
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x459f49
Code: ad b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 7b b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f054aeddc78 EFLAGS: 00000246 ORIG_RAX: 000000000000003d
RAX: fffffffffffffe00 RBX: 0000000000000004 RCX: 0000000000459f49
RDX: 000000008000000a RSI: 0000000000000000 RDI: 0000000000000000
RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f054aede6d4
R13: 00000000004c9e95 R14: 00000000004e1e90 R15: 00000000ffffffff
Shutting down cpus with NMI
Kernel Offset: disabled
Rebooting in 86400 seconds..